An enlisted soldier who killed five comrades apologized to the families of the victims and his own family in a note written before a suicide attempt, the defense ministry said Tuesday. He was in stable condition after surgery.

But the note did not contain any details indicating what prompted him to commit such an act that also wounded seven others at a border outpost, the ministry said.

The 22-year-old sergeant assigned to an eastern unit near the inter-Korean border town of Goseong was captured on Monday after sustaining a self-inflicted gunshot wound, two days after he went on a shooting rampage and fled with a rifle and a stash of ammunition.

Some 30 minutes before he shot himself in the chest, he demanded that the troops surrounding him give him a pen and a sheet of paper and he wrote a note.

"In the memo, Lim apologized to the bereaved families and his own. He also regretted how serious what he did was," defense ministry spokesperson Kim Min-seok said. "The rest of the content was an abstract description about his feelings."

"No details there indicate what led him to do such a behavior ... He did not write any complaints about military life or his comrades," he added.

But sources said bullying in the barracks may be to blame. Lim was on a list of servicepersons requiring "special attention" as he had difficulty in adapting himself to military life.

"After he gets recovered from the wounds, we will carry out investigations into him," the spokesperson said.

After undergoing surgery, he has been recovering in a hospital in Gangneung, about 240 kilometers east of Seoul, the ministry said, noting that he did not leave any messages or comments after being captured.

In the wake of the incident, the military is planning to review its system of managing conscripts.

"We want to ban commanders from arbitrarily changing the grade of each draftee on the list of extra attention and make it mandatory that changing the grade requires a review by the examiner," said an Army officer, requesting anonymity.

The military now has three classifications of its soldiers on the list for special care, and the rate is subject to change under the authority of commanders of each unit in accordance with the results of each soldier's personality test.

Lim had been classified as a Class-A soldier, which had banned him from conducting frontline service, but later was re-rated as Class-B, which means that he still needs special attention but is capable of carrying out the duty.

Among the country's some 500,000 conscripted soldiers, 3.6 percent were classified as the Class-A soldiers as of June, government data showed.

"We are also planning to implement the envisioned policy of sending at least one counselor to each regiment earlier than planned," he added.

Meanwhile, a steady stream of people visited a joint altar for the fallen soldiers set up in a military hospital in Seongnam, east of Seoul, the previous day. More than 500 colleagues and citizens paid their respects as of Tuesday morning, according to the defense ministry. (Yonhap)